The long term objectives of this project are to understand how temporal plasticity affects the function of primary auditory cortex (AI) circuits. To this end, the two specific aims in this project are: (1) evaluate spectrotemporal processing in normal auditory cortex; (2) evaluate the effects of temporal plasticity on AI of rats that have undergone perceptual learning for temporal modulations. The awake rat preparation will be used for physiological recordings. Multi-channel recording probes will be used to sample from neurons across all layers in AI. The class of neuron, fast-spiking (putative inhibitory interneuron or regular-spiking (putative excitatory neuron), will be determined from the recorded neural waveforms. From the data spectrotemporal receptive fields (STRFs) will be obtained and compared across layers and neuron classes. Another group of rats will undergo behavioral training for temporal modulations. Once long-term learning has been consolidated, AI will be examined for changes in spectrotemporal processing due to temporal plasticity. Changes in neural computations due to learning-induced plasticity will be correlated with layer and neuron class. These results will utilize STRFs to assess how the function of the cortical column in auditory cortex changes in response to temporal plasticity.